Elevator systems have hallway fixtures at each floor, including directional lanterns, hall call buttons, and in some cases, elevator position indicators. Traditionally, each hallway fixture on every floor was powered by means of wires run through the hoistway, with additional wires to provide signal communication between the floor and the controller, which has typically been located at the top of the hoistway in a machine room. To reduce the amount of wiring, modern systems use serial communication buses, which typically may require two wires for communication and two for power, one bus each for the lanterns and call buttons. The wiring requires significant installation time in new buildings, and makes modernization of existing elevators extremely difficult. Further, work in the hoistway is dangerous and should be avoided if possible.
The communication aspect of hall fixtures has been rendered wireless by means of radio frequency (or other) wireless communications. However, power is still required to be provided by wires, which must be specifically installed in the building during initial construction of an elevator system, or as a consequence of modernization.
Suggestions have been made to use very large coils disposed on the elevator car and the hoistway wall with large air gaps, such as the 30 mm (1.2 inch) running clearance between moving and stationary portions of an elevator system, which is required by typical regulatory codes, so that power can be inductively coupled from the car to the hoistway wall when the elevator car is at a landing, thereby to power the fixtures. It has also been suggested that magnetic coupling of power, such as between an elevator car and a hoistway wall, may be effectively achieved with coils having large C-shaped cores. However, it has been determined that large coils and C-shaped cores, with large air gaps, cannot effectively transfer the necessary power in a compact and efficient manner.